The day there's no one still sitting on the sidelines, wondering whether they should invest in Bitcoin or hold off for a pullback, is the day we should all sell because there's nowhere left to go but down. 
Most older people are skeptical of it, and rightly so; they've all seen plenty of asset bubbles before, and seen people try to pick themselves up from the wreckage left behind. We still don't know if this is a bubble or not, really... it's showing all the signs of it, in terms of the speed of growth and the euphoria of some of the participants, but as a currency it could of course be a different story. Gold is also largely held up by psychology rather than any valuable use cases or economic moat, but it's been there for thousands of years and is now considered one of the least risky investments rather than the most. When people first started digging shiny rocks out of the ground and making ornaments from them rather than throwing them at each other, I doubt any of them considered the investment value, and the first ones to start accepting it for food, water and other basic necessities were seen as absolute fools - just like, once upon a time, a pizza shop was seen as foolish for accepting 10,000 bitcoins instead of "real money."
Most older people are skeptical of it, and rightly so; they've all seen plenty of asset bubbles before, and seen people try to pick themselves up from the wreckage left behind. We still don't know if this is a bubble or not, really... it's showing all the signs of it, in terms of the speed of growth and the euphoria of some of the participants, but as a currency it could of course be a different story. Gold is also largely held up by psychology rather than any valuable use cases or economic moat, but it's been there for thousands of years and is now considered one of the least risky investments rather than the most. When people first started digging shiny rocks out of the ground and making ornaments from them rather than throwing them at each other, I doubt any of them considered the investment value, and the first ones to start accepting it for food, water and other basic necessities were seen as absolute fools - just like, once upon a time, a pizza shop was seen as foolish for accepting 10,000 bitcoins instead of "real money."